Soot removal compositions



Patented Sept. 9, 1952 soo'r REMOVAL COMPOSITIONS Joseph A. Chenicek, Bensenville, Ill., assignor to Universal Oil Products Company, Chicago, 111., a corporation of Delaware No Drawing. Application November 16, 1949,

1 Serial No. 127,789

8 Claims.

This invention relates to compositions of matter useful for the removal of soot from the interior surfaces of furnaces and boiler tubes normally coming in contact with the flue gases from the combustion of hydrocarbonaceous fuels. More specifically, the invention concerns soot removal compositions comprising volatile and relatively stable copper chelate compounds and halo-substituted hydrocarbons and relates further to the process for the use of such compositions in the removal of soot.

It has heretofore been generally recognized that the introduction of a copper halide salt, and particularly copper chloride, into the combustion zone of a furnace utilizing a hydrocarbonaceous fuel has a limited effect in the removal of soot accumulations within the furnace and adjacent portions of the furnace which contact the flue gases therein, such as boiler tubes, presumably based upon the catalytic action of the copper halide salt in oxidizing the carbon and carbonaceous materials in the accumulation of soot. The copper halide salt is believed to be at least partially volatilized in the combustion zone and the vapors of copper halide salt in the presence of excess oxygen cause the removal of soot through oxidation and the resultant formation of the gaseous oxides of carbon. Copper halides as such, however, are relatively non-volatil and the salt vapors do not reach the soot accumulation in sufficient quantitites to effectively remove all of the soot deposit without repeated introduction of the copper halide salt into the combustion zone. It is an object of this invention to provide soo-t removal compositions comprising volatile copper chelate compoundsin admixture with .chlorohydrocarbons which volatilize upon introduction into the combustion zone, ionize by decomposition, and form copper chloride in situ at the source of the soot deposit. The resultant copper chlorides in the presenceof excess oxygen in the flue gases catalyze the oxidation of the soot and effectively remove the same from the interior walls of the combustion zone, from the exposed boiler tubes and from the smoke stack. The use of the present soot removal composition in furnaces employing hydrocarbonaceous fuels results in greater heat transfer efficiency, especially in furnaces employing boiler tubes, and the maintenance of maximum draft in the combustion zone by removal of sooty accumulations which hinder the flow of exhaust gases through the stack pipes.

The use of the present soot removal composition further eliminates th more expensive and less efiicient mechanical methods for soot removal heretofore employed by the art.

In one of its embodiments the present invention relates to a soot removal composition com prising a mixture of a copper chelate compound volatile at normal furnace operating temperatures and a chlorohydrocarbon.

A more specific embodiment of the invention concerns a soot removal composition comprising a mixture of a copper chelate of a beta-ketonic organic acid ester and a chloro-substituted aliphatic hydrocarbon, said mixture containing said copper chelate and said chlorohydrocarbon in such proportion that the atomic ratio of total chloro radicals to total copper is at least 2to 1.

Other objects and embodiments of the invention relating to specific aspects of the soot removal com-position and the process for utilizing the same in th removal of soot will be referred to in greater detail in the following further description of the invention.

Copper chelate compounds are a specific and well defined class of metallo-organic compounds of the complex coordination type in which the metallo-organic bonds joining the metallic and organic radicals of the compound are of the ordinary and coordination types oscillating in alternate positions. Copper salts, as well as other metallic salts, are capable of entering into a chelate type of coordination complex with certain classes of organic compounds such as the ortho-substituted phenols (salicylaldehyde, for example), 0- hydroxysulfones, o-nitrophenols, beta-aminocrotonic esters, monohydrazones of 1,2-di-ketones, di-ethylene-triamine, bis-acetoacetonylethylenediamine, phthalocyanine, etc., th coppe chelates of the beta-ketones and beta-'ketonic acid esters being particularly desirable in the present soot removal composition because of their desirable volatility at normal furnace operating temperatures and their thermal stability at their boiling points. The latter preferred beta-di-ketones having the eneral formula:

H RCOCHZOR and the beta-ketonic acid esters having the general formula: RCOCHzCOOR, representative of the general class of chelate-forming organic compounds, have the capacity of entering into a chelate coordination complex-type of structure by virtue of their ability to enolize under normal conditions to form an equilbrium mixture of the ketonic and enolic forms of these compounds, the respective enolic formulas of these compounds being RC=CH(H3R The chelate coordination complexes of a betaketonic acid ester, for example, have the following general structure:

I no

Typical representative beta-diketone compounds me, by merely admixing a copper salt, preferably of an organic acid, such as copper acetate, with a chelateforming organic compound such as acetylacetone and thereafter separating the resulting copper chelat'e complex from the reaction mixture, as forexample, by fractional distillation.

The copper chelate coordination complexes are usually soluble in chlorohydrocarbons and may be admixed therewith, generally in any desired proportions.

7 The chlorohydrocarbon component of the present soot removal composition is preferably selected from the aliphatic chloro-substituted hydrocarbons, although several species of the chloro-substituted naph'thenes are also effective in sootremoval compositions when admixedwith the copper chelate coordination complex. Thus, such chloroi-substituted alkanes andcyc1o-alkanes as carbon tetrachloride, ethylene (ii-chloride, trichloroethane, tert-butylchloride, chloro-cyclopentan'e, hexachloro-cyclohexane, etc. are utilizable in the present soot removal composition which not only supply the chloro radicals requisite in thee formation of the copper chloride in situ while the components of the composition are in their vapor state but, further, act as solvents for the copper chelate coordination complex in the preparation of the soot removal composition. The proportion of the respective copper chelate compound and the chlorohydrocarbon components in the soot removal composition is dependent upon their respective molecular weights and, in general, on the number of chloro groups substituted in the chloro hydrocarbon component. Thus, theoretically, 'inorder to utilize all o f the copper in'a given charg'eof the soot removal composition, the atomic ratio of total chloro radicals available from the chlorohydrocarbon component to copper must be at least 2 to 1, and'is preferablyg'reater, up tojabout 5 to 1 to insure substantially complete conversion of the copper in the charge to the'corresponding copper'chloride salt. When utilizing a di substituted chlorohydrocar bon, it thus becomes necessary, in order to obtain substantially complete conversion of the copper chelate to the corresponding copper chloride salt,

to utilize a molar proportion or the di-emorm substituted hydrocarbon, whereas in the utilization of a tetra-chloro-substituted chlorohydrocarbon, the molar ratio of copper chelate to chlorohydrocarbon required is 2 to 1.

In the utilization of the present composition for the removal of soot from furnace walls, boiler tubes or smoke stacks, it may be added to the hydrocarbonaceous fuel prior to combustion, as for example, by spraying the composition on the surface of a solid hydrocarbonaceous fuel, such as coal, or admixing the same with, a liquid hydrocarbon fuel prior to introducing same into the combustion chamber of the furnace, by spraying the liquid composition into the furnace during combustion or injecting the composition into or onto the fuel bed during combustion. The subsequent vaporization of the copper chelate and chlorohydrocarbon into the flue gases carries the active components to the surface accumulation of soot deposits with which'the flue gases come into contact and catalyzes the oxidation of the soot Which disappears in the flue gases as oxides of carbon. The resulting soot-free surfaces in the heat transfer zones of the furnace havegreater heat transfer efficiency without the necessity of resorting to mechanical removal of .the soot therefrom.

The preferred copper chelates and halohydrocarbon components constituting the present soot removal composition have been indicated above, but in thus specifying the preferred components, it is not intended thereby to limit the general scope of the invention in strict accordance therewith; other volatile copper chelates and chlorohydrocarbons which are'stable at theirvaporization temperatures may be utilized as components of the composition Without departing from the basic principles upon which the present invention is based.

Example A chelate complex of copper-acetate and acetylacetone is mixed with carbon tetrachloride in a molar ratio of copper chelate to carbon tetrachloride of 2 to 1. The resultant soot removaljcomposition is utilized for its intended purpose by spraying it on the surface of coal prior to introducing the latter into the combustion chamber of a furnace.

I claim as my invention:

1. Ascot removal composition consisting of an admixture of a coppenchelate compound capable of volatilizing at normal furnace operating temperatures and a volatile chlorohydrocarbon in a pro-portion to provide a total chlorine tocopper atomic ratioof at least 2 to 1.

2. The composition of claim 1 further characterized in that said copper chelate component is a chelat'e coordination complex of a copper salt and a beta-diketon'e capable of existing'in its enolic form.

3. The composition of=claim 1 further characterized in that said copper chelate is a chelate coordination complex of a copper salt and a betaketonic acid ester capable of existing inits enolic form. r

'4. The composition of claim 2 further characterized inthatsaid'beta diketone is 'acetyla'ce tone. 7

'5. The composition of claim 2 further characterized in that said beta-ketone is propionylac'etone.

6. The composition of claim '3 further charac- 5 6 terized in that said beta-ketonic acid ester is an REFERENCES CITED aliphatic alcohol ester of acetoacetic acid. The following references are of record in the 7. The composition of claim 1 further characm f It n terized in that said chlorohydrocar bon is a polye 0 15 pa 8 chloro substituted aliphatic hydrocarbon. 5 UNITED STATES PATENTS 8. A process for removing soot from the inner surfaces of a furnace utilizing a hydrocarbonagg v L l z J 1 ceous material as fuel which comprises introduc- 2144654 Githmeann E' ig 1939 ing into the fuel bed of said furnace during its 2287235 Flint et all 1942 operation a soot removal composition consisting 10 of a volatile copper chelate compound and a chlo- OTHER REFERENCES rohydrocarbon in a proportion to provide a total Bulletin 360, Bureau of Mines, 1932, 231 and chlorine to copper atomic ratio of at least 2 to 1.

JOSEPH A. CHENICEK. 

1. A SOOT REMOVAL COMPOSITION CONSISTING OF AN ADMIXTURE OF A COPPER CHELATE COMPOUND CAPABLE OF VOLATILIZING AT NORMAL FURNACE OPERATING TEMPERATURES AND A VOLATILE CHLOROHYDROCARBON IN A PROPORTION TO PROVIDE A TOTAL CHLORINE TO COPPER ATOMIC RATIO OF AT LEAST 2 TO
 1. 